There are several different types of picture frames commercially available today. The standard rectangular frame is constructed from four straight members connected at mitered ends using one of a variety of fasteners at each of the four corners. The frame members may be made from a variety of materials including wood, plastic and extruded or formed metal, such as aluminum.
Among the metal picture frames commercially available, there are two types of interest. First, a "side-loading" type of metal frame must be assembled, effectively around a picture laminate, thereby "capturing" the picture within an inwardly directed channel. The term "picture laminate is used to collectively describe a layered assembly including at least one of the following: a picture, a backing, a front sheet of glass or plastic, and a matte board. The picture laminate is inserted into the channels of three connected frame members (side loaded into the frame) and held in position by the securing of the fourth and last frame member to the other three members. Each frame member of the side-loading type of metal frame includes a structure having two channels which provide longitudinal rigidity to the frame member, and therefore, a strong assembled frame. Owing to its strength, this type of picture frame is suitable for large and/or heavy pictures where the weight of the picture may otherwise sag or bow other types of non-reinforced, less-rigid frame members.
Although the side-loading type of picture frame is useful in framing large and/or heavy pictures, the frame members are expensive to manufacture and the connecting system required to secure each frame member together is relatively complex, making assembly of a side-loading type of frame a time-consuming procedure.
As shown in FIGS. 1-3, labelled "Prior Art", a second back-loading type of metal prior art picture frame includes a corner joining bracket or clip 10 (hereinafter called "clip 10"), a first frame member 12, and an adjacent second frame member 14. Clip 10 comprises two transverse legs 26 and is typically made from a flat steel stock. It includes a longitudinal axis 16, an upper edge 18, and a lower edge 20.
Located along both upper edge 18 and lower edge 20 of each leg 26 of clip 10 is at least one slot 28. The prior art clips 10 typically include two slots 28 positioned along upper edge 18 and lower edge 20 of each leg 26, as discussed below, and as shown in FIGS. 1-3.
Frame members 12, 14 are usually metal and manufactured through an extrusion or metal forming process. The frame members 12, 14 shown in FIGS. 1-3 are two of a typical four frame member set used in the making of a conventional rectangular frame. A mitered cut (at forty-five degrees) is formed at each end of frame members 12, 14 so that when secured end to end, the combined angle ninety 90 degrees.
Formed integrally with each frame member is a side wall 30 having an outer surface 32, an inner surface 34, an upper edge wall 36, a lower edge wall 38. A front wall 40 is formed integrally with lower edge wall 38 and oriented generally perpendicular to side wall 30 and directed inwardly (towards the center of a completed picture frame). Front wall 40 includes an outer surface 42 and an inner surface 44. Extending perpendicularly to and formed integrally with inner surface 42 of front wall 40 is a lower deformable flange 46. An upper deformable flange 48 is similarly formed integrally with and extends perpendicularly from upper edge wall 36. Upper and lower deformable flanges 46, 48 are coplanar and directed towards each other. The distance between inner surface 34 of side wall 30 and deformable flanges 46, 48 is approximately equal to (or at east slightly greater than) the thickness of clip 10. Deformable flanges 46, 48 and inner surface 34 together define a fastening channel 50 which is sized and shaped to snugly receive a single leg 26 of clip 10.
Referring to FIGS. 2 and 3, two adjacent frame members 12, 14 have been fitted together along two adjacent mitered ends using clip 10. Each leg 26 of clip 10 is positioned within fastening channel 50 of each frame member 12, 14 so that the mitered ends tightly abut each other. Once in position, as described in greater detail below, and at predetermined press points 52, a portion of each deformable flange 46, 48 is displaced inwardly (using a pneumatically powered crimping machine, not shown) into fastening channel 50 (towards the inner surface 32) through slots 28 of clip 10. The press points engage within each respective slot 28 of clip 10 and bind each respective leg 26 within fastening channel 50. The result is that clip 10 is pressed into a holding position within fastening channel 50 thereby securing two adjacent frame members together.
Once a back-loading type of picture frame is assembled, the picture laminate is loaded to the frame from behind and secured to the frame using appropriate spring-clips.
Although the back-loading type of metal picture frame is less expensive to manufacture and easier to use compared to the side-loading type of frame, it lacks rigidity and longitudinal strength and is therefore susceptible to sagging or bowing under the weight of a large or otherwise heavy picture. When a heavy metal frame is hung, the weight of the frame and picture can exert an inward force on the vertical frame members, causing them to sag. Deformation of the vertical frame members will, in turn, cause the upper and lower horizontal frame members to bow. In extreme situations, the bowing of the horizontal members can dislodge the connectors in the corners of the frame which are used to hold adjacent frame members together.
Furthermore, the pneumatically powered crimping machine used to attach each frame members to a corner clip is expensive to manufacture and potentially dangerous to operate. Pneumatically powered machines perform a prescribed crimping procedure once triggered by an operator. The actual crimping operation is completed automatically very quickly and is not directly controlled by the operator (after triggering).
It is therefore an object of the invention to provide a crimping machine for crimping corner clips to respective frame members of back-loading type picture frames which is portable, inexpensive to manufacture and safe and easy to operate.
It is another object of the invention to provide a cross brace that may be quickly and easy secured to and removed from a back-loading type of picture frame to prevent sagging and bowing of the frame after it has been hung.